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L. LEE 'lI April zo, 1954 FUEL AND SPEED CONTROL APPARATUS FOR TURBOJET ENGINESl April 20, 1954 LEE Il; 2,675,674

FUEL AND SPEED CONTROL APPARATUS FOR TURBOJET ENGINES Filed May 9, 194'?` 5 Sheets-Sheet 2 Fly 2 M INVENTOR. f3 Lezg/fo/:eel

"Y- AM" Pl/MP L. LEE IL April 20, 1954 FUEL AND SPEED CONTROL APPARATUS FOR TURBOJET ENGINES Filed May 9, 1947 5 Sheets-Sheet 5 www Qmvkm NEN oww W FUEL AND SPEED CONTROL APPARATUS FOR TURBOJET ENGINES Filed May 9, 1947 L. LEE 1L April 20, 1954 5 Sheets-Sheet 4 www QQ gill@ s hsv im. N

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FUEL AND SPEED CONTROL APPARATUS FOR TURBOJET ENGINES Filed May 9, 1947 l.. LEE lI April 20, 1954 5 Sheets-Sheet 5 INVENTOR. @{gfa/z le@ I Patented Apr. 20, 1954 UNITED STATES PATENT OFFICE 32 Claims. (Cl. Gil-39.28)

This'invention' relates to fuel and speed control apparatus for prime movers and especially to sucn apparatus for internal combustion engines inclusive of. gas turbine and jet engines.

My invention is more particularly applicable to interna-l combustion engines suitable for propeller-propulsion, jet-propulsion, or propellerand-jet propulsion of.' aircraft'. Such engines usually include an. air inlet,A an air compressor, one or more combustion chambers,` a' gas turbine, and atail pipe'forf discharging combustion gases to the atmosphere. Associated with the eng-ine a iuel system including a fuel pump for delivering fuel to the" combustion chambers. My invention. concerns apparatus to control thek engine speed. and power by controlling the fuel pump delivery as a functionV of several variables including engi-ne'speed, engine temperature', other engine opera-tingl conditions, and manual control.

Swing to structural and. metallurgical restrictions, engines of the type referred to may not be safely operated at speeds or temperatures exceeding predetermined limiting values, but for maximum economy of operation, both speed and temperature of the engine must be maintained at or near these values. On the other hand, engine speed. is a critical factor in night periormance of aircraft and an. engine' may not be used at maximum allowable speed. in all flight maneuvers, at. all night speeds, or under all-.night conditions. In. multiple engine installatimes,V it is preferable to operate one or more engines at. substantially full speed and power while variations in the total power output are obtained by controlling. that of one engine, rather than to operate all engines at correspondingly reduced speed and power, Fuel controlapparatus must be provided which enables the operator to vary the engine speed as desired from a minimum value at starting speed. and minimum power to the predetermined limiting. speed and iull power. The control of engine temperature is preferably a substantially automatic function of the fuel control apparatus.

The value of engine speed corresponding to any given value of fuel flow varies as a function of. the altitude of night, flight speed, air density at the engine air inlet, engine torque, fuel quality and a wide variety of other factors. For precise regulation of engine speed or to avoid excessive temperatures, therefore, it is not feasible to rely solely upon automatic regulation of fuel ow as a function of variables which exclude engine speed and temperatures.

Objects of my invention are:

(l) To provide improved fuel. and speed control apparatus for Aan internal combustion engine 2V employing fourcomponent coordinated hydraulic systemsk for regulating the fuel delivery, said systems being respectively responsivel to manual controland tov pressure, temperature, and speed conditions of the engine;

2.) To provide in such apparatus improved cam and lever mechanism for modifying thev op*- eration. of the manual system by the pressure responsive system;

3) To provide improved pressure regulating and pressure responsive control elements which may be used in hydraulic apparatus-such as above described (4) To provide in the temperature responsive control' system in such: apparatusA improved .means for automatically' resetting the apparatus to perhigher engine' temperatures in a predetermined emergency range of operation than in a corresponding normalrange of operation;

(5=)f To provide in apparatusI such as described improved assembly of component parts of said apparatus including three separable principal castings having all Working parts mounted thereirror' thereon and having a removable domesh-aped. cover for permitting. ready access to all parts assembled. inand on one of said principal castings;

(.6) To provide an improved arrangement of external. connections to such apparatus including a main drive sha-ft on. the centerline of a fluid pump and a speed governor means for simultaneously operating said. pump and said governor means, and a. mai-n control shaft having adj-acently thereon a pai-r of cams for operation of the manual and speed control systems;

(7') To' provide in such apparatus improved means for controlling acceleration and deceleration of the engine as a function of said pressure responsive system; and.

8) To provide improved means responsive to the control. shaft for predetermining the engine speed including adjustable-means for preselecting. a maximum-.value of speed independently of operation of. the control shafts.

Other objects and advantages of my invention will become apparent from. a consideration of the appended specication, claims, and drawings, in which:

Figure l shows,A somewhat diagrammatically, an. engine suitable for propeller-and-jet propulsion of aircraft, together with its associated fuel pump and an engine control. lever, there being also shown principal connectionsl between the engine and a diagrammatic illustration of the fuel and speed control apparatus of Fig. 2;

` Fig. 2 shows, also somewhat diagrammatically,

fuel and speed control apparatus embodying an hydraulic control system for regulating the engine fuel pump according to the principles of my invention;

Fig. 3 is a cross-sectional elevational view of the apparatus shown diagrammatically in Fig. 2, taken on the line 3 3 of Fig.` 6, showing the main drive shaft and portions of the speed and pressure responsive control systems;

Fig. 4 is a cross-sectional elevational View of the apparatus of Fig. 3 except for omission of the mounting flange, taken on the line 4 4 Vof Fig. 6 in which principal elements of the manual and pressure responsive control systems are chiefiy shown; y

Fig. 5 is a cross-sectional elevational viewfof the apparatus of Figs. 3 and 4, taken on the line 5 5 of Fig. 6, showing the control shaft and other elements of the apparatus; l

Fig. 6 is a cross-sectional plan view of th apparatus of Figs. 3, 4 and 5, taken on the line 6 6 of Fig. 3 on which are indicated section lines 3 3, 4 4, 5 5, and I 'l for identifying the respective locations of the sections shown in Figs. 3, 4, 5, and '7;

Fig. 7 is a cross-sectional elevational view taken along the line I 'I of Fig. 6; and

Fig. 8 is a fragmentary cross-sectional view taken along the line 8 8 of Fig. 7.

l Figure 1 Referring to the drawing, Fig. l, there are shown the principal elements of the engine above referred to, a supporting casing I0, an air inlet I2, a multistage compressor I4, a compressor rotor shaft IS, one each of a number of combustion chambers I8, one of a corresponding number of fuel discharge nozzles 2B connected to a generally circular manifold 22 by means of a conduit 24, a multistage turbine 26, a turbine rotor shaft 28 connected to the compressor rotor shaft I5, a tail pipe 30 for discharging combustion gases from turbine 26, a center bearing 32 and end bearings 34 and 36 supported by casing Il), a propeller shaft 38 to which is fixed a propeller 4i), and a gear train 42 connecting shafts I6 and 38 for rotating propeller 4I) at a speed proportional to engine speed and for operating the fuel pump and other accessories. Construction of a jet engine used solely for jet propulsion is similar to that of the engine of Fig. 1 except for omission of the propeller and propeller shaft and corresponding modification of the gear train. Since, in a jet engine, the power developed by the turbine is used only for operating the compressor and accessories, single-stage rather than multi-stage turbine construction is generally employed.

A fuel pump 44 has associated therewith delivery varying means diagrammatically shown at 46. Pump 44 is connected to a pump inlet co'nduit y48 and to a pump discharge conduit 50. Fuel flows from the indicated source of supply through inlet conduit 48, pump 44, and pump discharge conduitr5 to manifold 22 in the engine. Pump 44 is operated by a drive shaft 45 connected to gear train 42 in the engine, or any other suitable source of power. The delivery varying means is responsive to a variable control oil pressure (pc) in a conduit 5S which is regulated by the control apparatus of Fig. 2.

In each of the discharge nozzles there is a series of fixed slots, one of which is indicated at 2 I, through which fuel enters the nozzles from conduits 24. The fuel flow from thek nozzles is 4. directly proportional to the effective area of slots 2| and is a square root function of the drop across the slots between the pressure in conduits 24, which is substantially equal to the pressure (pF) in conduit 5U, and the pressure in the combustion chamber. It follows, therefore, that the fuel pump delivery is a function of the pressure (pF) in conduit 50 which is controlled by the delivery varying means 46.

When it is desired to limit the range of fuel pressure so that its value at maximum fuel flow is less than that corresponding to the square root function of the drop across slots 2|, the nozzles may be provided with auxiliary slots supplied by another manifold connected to conduit 50 through a pressure-responsive flow-divider which opens at a predetermined value of the pressure (pF). In this manner the pressure (pF) may be maintained sumciently `high to produce satisfactory nozzle discharge without requiring the pump to operate under unfavorable pressure conditions at maximum flow.

The control apparatus of Fig. 2, diagrammatically shown in Fig. 1, is connected to a source of compressor dischargeV pressure (19D) in the engine by a conduit 52 and to a corresponding source of compressor inlet pressure (19E) by a conduit 54. As subsequently explained, the control apparatus is responsive to the pressure differential (pn-10E) which is an indication of air flow through the engine. The value (pn-22E.) increases as the engine speed increases, as flight speed increases, and as the altitude of flight or entering air temperature decreases, and is also a function of the compressor characteristics.

A main drive shaft 58 (Figures 1 and 2) in the control apparatus is driven by the engine at a speed proportional to engine speed and a main control shaft 6U is rotatable in response to movement of a shaft 52 to which is fixed an engine control lever 64. Control lever 64 is manually operable in reference to a scale 68 on a fixed quadrant 66, scale '68 lbeing calibrated in terms of degrees in relation to R. P. M. engine speed.

Figure 2 Referring to Fig. 2, there is shown somewhat diagrammatically an embodiment of my invention all principal elements of which, excepting a thermal control l0, are enclosed in a casing I2 having external connections with conduit 52 for supplying air to the apparatus at the compressor discharge pressure (pD) with conduit 54 for supplying air to the apparatus at the compressor inlet pressure (71E), and with conduit 56 for transmission of the variable control oil pressure (pc) from the apparatus tov the fuel pump delivery varying means 46 shown in Fig. 1. Casing 'i2 as shown in the drawing is of continuous cross-section but for purposes of manufacture and assembly may be made in an equivalent form comprising two or more separable elements as is the case in the embodiment of Fig. 3.

The control apparatus of Fig. 2 is a self-contained hydraulic system employing the interior of casing 'I2 as a reservoir 'I4 which is maintained approximately full of suitable hydraulic fluid at the pressure (p) in order to permit the working elements to operate in an oil bath and which is vented at a threaded port 'I6 to the atmosphere or other desired pressure source. If desired, reservoir 'I4 may be made a part of the oil system of the engine. In this case, a pair of plugs 'I8 and otherwise serving as drain plugs are removed from casing I2 andl the respective casing openatraen ings aren then connected. by'suitableinlet-` andI outlet conduits to the engine: oil system. The. main drive shaft. 58 operates an hydraulic pump 82 which pumps iiuidfrom. reservoir 14 through an inlet port 84 andan. outlet 8'6 into a chamber 88. The'pressure (4m-)- inv chamber 88 is maintained at a substantially constant value, approximately 240 p.l s. i. in they embodiment shown, by arelief valve 90, which allows uid to iiow from chamber 88 past valvef90f, through a chamber 94 and an aperture'98 to reservoir 14 in opposition to.y a substantially constant force produced by a valve spring 98. Fluid from chamber 88 enters two main fluid conduits |04 and |06` downstreamv from a filter |00, andis conveyedk at pressure (p1) to elements of. the apparatus hereinafter specified- The control apparatus comprises four mechanically and hydraulically cooperative component systems, as briefly outlined in the immediately following numbered paragraphs, for: regulating the variable control oil pressure (pe) namely:

('1)v A manual control system principally including a main servo valve |08, a main servo valve sleeve |09,y a main power piston l0, a main floating lever |'|2, a push rod |I|4, and a cam |-6 fixed to the main control shaft 80, for rendering pressure (20c) variable by movement of theengine oontrol lever 84, Fig. l. Also` included intheV manual control system, as set forth herein, is a lever mechanism. |32 comprising. a pair of levers |94 and |98, a circular bearing 208 between said levers, a spring 204, anota-rod' |92 for loading piston with a force due to spring 204. Fluid flows discoritinuously to the manual control system throughl a conduit I|.8 connected to main fluidconduit |08' and is drained from the manual control system through an outlet passage opening into reservoir 14 at the upper end of valve sleeve |09. Thev variable. control oil pressure (pe) is transmitted from the manual control system through a conduit |22 whichis connected. -to conduit 56.

(2) A barometric control system principally including a barometric/servoy valve: |24, a barometric servo valve sleeve |25, a barometric power piston |26, a barometric iioating lever |28, a fixed elongated barometric cam |130, a positioning bar 288 for varying the position of bearing 208; and a pai-rY of bellows |34 and |86Y respectively connected' to conduits 52 and 54. The pressure (per is made a cated at- |42., a governor lever |44, agovernorpush rodv assemblyl |48, a setting lever |48, a cam |50 on the main control shaft 60, and an overspeed power piston |52. In this system the pressure (pc) is made a function of the engine speed by modifying movement of the main floating leverV ||2 oi thev manual control system in. response to movement of the overspeed power piston |52. Fluid iiows discontinuously to the governor valve mechanism |42 through conduit ber |54 opening intovfreservoir 1A.

|04 and isA drained from that valve. mechanism through: a. chamber |54 in agovernor valvesleeve |58, cham 6: (14) Al thermal control system including the thermal control 10 and a thermal piston |55- for;

overriding the manual control system; as a function of the engine temperature'. Normally, there isA no flow of fluid through the thermal controll system, but when the predetermined limiting or maximum allowable temperature is exceeded fluid iiows: from main fluid conduit |06, successively through a conduit |51, past piston |55, and through a conduit |00, thermal control 10, and a conduit |62: to*r reservoir 14. Under conditions later described, fluid is also supplied to the ther'- mal' control system through a conduit 314.

M anaal control system A wall |64 is provided in. reservoir 14 and is suitably bored or otherwise machined. for housing and operation therein of some elements of each of the four component control systems previously defined.

In the manual control system, a gear |86 is provided at one end of main servo valve sleeve |09 for rotation of the sleeve in wall |64, sleeve |09` being installed with gear |68 at thelower side of wall |164.Y and having, its upper end extendingY somewhat beyond the upper side of the wall. Gear |66 and hence sleeve |09 are rotated by another gear 8.8 fixed to a shaft |10 which in turn is driven from the main drive shaft through. a suitable connection (not shown in Fig.. 1) Similarly, a gear |14 is provided at the upper end of piston H0 which is both slidably and rotatably operable in wall |04 and is installed with gear |14 above the wall. Gear |14. is rotated by another gear |16 iixed to the upper end of shaft |10.

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Any other means of suitably rotating sleeve |09 and. piston ||0 may be employed, the purpose ofr such.. rotation being to avoid sticking of the main servo valve |08 insleeve |09 and to prevent sticking of the piston in wall |64.

Valve sleeve |09 is provided with a pair of parallel circumferential grooves |18 and |80 and one or more corresponding ports |82 and |64 f drilled radially at they vertical centers of the grooves.v The upper end of conduit ||8 opens opposite groove |18 and ports |82 are therefore continuously supplied with fluid at pressure (p1) Groove |y is similarly connected tothe upper end of. a passage |80` which is connected to conduit |22.

Valve |08 is undercut to form an annular chamber |88 and has a neutral position as shown inFig. 2. in which the lower edge of the undercut is alined with the upper edge of port |82, and

the upper edge. of the undercut is alined with the lower edge of outlet passage |20. Ports |84 communicate with chamber |86. regardless of the position oi valve. |00 in its normal range of operationY When valve. |88 is displaced. downward. so that portV |82y opens into. chamber |88', a path for flow is provided. which. successively includes conduit H0,r groove |18, ports |02, chamber |86, ports |84, groove |80, passage |88, and conduit |22, at the upper endV of which there is an ex-v pansible chamber |90 included between the lower end of piston H9 and wall |04. The value of the variable control oil pressure (pe) in conduit 56 and chamber |90 is thus increased upon downward movement of valve |08 from its neutral position. Similarly, when valve |08 is displaced upward so that chamber |80 opens into outlety passagev |20, a path for flow is provided from conduit 58 and chamber |90, through passage Y |08, groove |80, ports |84, chamber |86, and-out.-

7 let' passage |20 to reservoir l14; the-pressure (pc) being thereby decreased. i L

-The left-hand end of main floating has a pin-and-slot connection ||3 with rod |92 which has a self-alining connection 'at its lower end with the bored interior of piston' |`|0 so that vertical movement of the piston producesr upwardmovementof rod |92 and simultaneously allows angular displacement of the rodwith respect to the piston without causing the latter to bind in wall |66. The upper end of rod |92 is hinged to the left-hand end of lever |94 in mechanism |32,.lever |94 having its right-hand end hinged to a fixed support |96. Above lever |94, mechanism |32 includes the lever |98 which has its left-hand end hinged at a pin 200 fixed in a support 262 above and approximately on the center-line of piston H0. The right-hand end of lever |98 is connected to tension spring 204 which has its lower end anchored in a xed support 206. A measure of the downward force of spring 204 is transmitted from lever 98 to lever |94 through the circular bearing 208 the position of which is regarded as fixed in the present discussion. Piston is subjected to an upward force proportional to the differential (pc-p) between the respective pressures in chamber |90 and reservoir 'I4 and to a measure of the downward force of spring 204 which is transmitted to the piston through lever mechanism |32 and rod |92. The rate of spring 284 is high, so that the value of the differential (pc-p) and hence the variable control oil pressure (pc) may vary throughout a wide range of values corresponding to a relatively narrow range of movement of the piston which is positioned to maintain the forces acting thereon in equilibrium.

While the drawing shows the right-hand end of main floating lever |2 engaged with a finger 2|0 pinned to a rod 2|2 which is fixed to the upper side of the overspeed power piston |52, when considering the manual control system independently of the speed control system, as in the present discussion, it may be assumed that the right end of lever ||2 is free, whence the lever is positioned by: (l) push rod ||4 which carries an arm 369 engaging an adjusting screw 2|4 threaded into lever ||2 and locked in place byL means of a nut 2|6; (2) rod |92 which serves as a pivotal support for the left-hand end of lever ||2; and (3) a light spring 2|8 compressed between a fixed support 220 and a retainer 222 supported by the upper end of valve |08, which causes the adjusting screw 2|4 and hence lever ||2 to follow movement of push rod 4 as the latter is actuated by cam H6. It is noted from the above that, excepting the substantially negligible force due to spring 2 8, the main servo valve |08 does not directly affect the position of lever ||2 but instead is positioned by the lever, there being equal and opposite forces proportional to pressure (p) on the ends of valve |08. When considering the manual control system only, the position of bearing 258 and hence the downward force of rod |92 corresponding to any given position of piston ||0 is regarded as fixed. In the neutral position of servo Valve 08, as shown, the manual control system is in a state of equilibrium; i. e., there is no flow of fluid in the system, the pressure (pc) is such as to maintain piston I0 in a position corresponding to the position of cam ||6 and the neutral position of valve |08, and the pump delivery corresponds with the value of pressure (pc) trapped in the system by closure of the servo valve.

leveruz Upony clockwise movement of control lever 64,7' Fig.- l, and consequent clockwise movement ofi maincontrol shaft S6 and cam ||6, lever ||2y moves clockwise about connection ||3 and servov valve |09 is depressed from its neutral position.

Consequently, as previously explained, the value of pressure (pc) and hence the fuel flow to thel engine increase. Pressure (pc) continuesto increase until piston ||0 responds by raising lever ||2 and valve |08 avsuicient amount to restore the valve to its neutral position, following which no further change occurs as long as the position of shaft 60 remains undisturbed. Similarly, upon counterclockwise movement of control lever |54,`

Fig. 1, and corresponding counterclockwise movement of shaft 60 and cam HB, lever ||2 moves counterclockwise about its connection with rod |92 and the servo valve is elevated above its neutral position. In this case, las previously explained, the value of pressure (pc) and hence the fuel ow decrease, continuing to do so until piston l 0 responds by lowering rod |92 and lever ||2 to a new position at which servo valve |08 is again restored to its neutral position. When servo valve |08 is in its neutral position, the value of pressure (pc) and hence the fuel flow is determined by the position of control shaft 60 for a given xed position of bearing 208 in lever mechanism |32.

As stated earlier, the engine speed corresponding to any given value of fuel now varies as a function of entering air density, night speed, and other factors over which the manual control system has no control and to which it is unresponsive.

variable control oil pressure (pc) from minimum to maximum values corresponding to a predetermined range of clockwise movement of the engine control lever 64, Fig. 1, and depending upon the downward force transmitted by rod |92 to piston ||0.

Speed control system Governor valve mechanism |42 includes a flyball speed responsive device 224 operated by the main drive shaft 518 for varying the vertical position of governor valve sleeve |56 as a function of engine speed. The valve sleeve operates in a suitably bored projection 225 of casing 12. The inner race of a ball bearing assembly 226 is fastened to the upper end of sleeve |56 and the outer race of bearing assembly 226 supports a lower governor spring retainer 228 which is slotted so that lever |44 and retainer 220 are independently movable in relation to each other in a vertical plane. Setting lever |46 is pivoted approximately at the center of its length on a fixed pin 230 and has its right-hand end supported by a follower push rod 232 in governor push rod assembly 46. A governor spring 234 is compressed between lower retainer 228 and an upper governor spring retainer 236 which is forced upward by spring 234' against the left-hand end of setting lever |48. Bearing assembly 226 permits sleeve |55 to rotate while retainer 228 remains stationary and hence prevents torsional stress in spring 234.

Push rod assembly |45 is actuated by cam |50 in response to movement of the engine control lever 64, Fig. 1, for varying the position of setting lever |48 and the upper governor spring retainer 236, and hence for varying the load of spring 234 on valve sleeve |56 in opposition to the upward force of the speed responsive device 224. As-

It follows, therefore, that the manual con-I trol system provides a means of regulating the sembly |46 includes the follower push rod 232 having its lower Vend slidably operable in a hollow sleeve formed on the .upper end of a push rod 1238 engaging cam |50. During a predetermined range of movement rof control lever 6.4 in which the engine speed s manually variable, a spring 240 maintains the overall length of the assembly |46 at a value vdetermined by engagement of a pin 242 in push rod 233 with the lower end vof -a slot 244 in follower push rod 232. When, however, setting lever |48 engages .an adjusting screw 246 so that further upward movement of rod 2.32 is prevented, upward movement of push rod '238 is permitted by compression `of spring 249, the length of slot 244 and the distance 4between the lower end of rod 232 and the lcorresponding por tion of rod 238 being sufficient to prevent jamming of the push rod assembly.

In the particular embodiment shown, the downward force of governor spring 234 varies substantially directly with the spring deflection, while the upward force due to speed .responsive device l224| is proportional to 'the square .of the engine speed. When these forces .are in equilibium, there is no vertical movement of :sleeve 1.56. The position of the sleeve corresponding :to a condition of equilibrium may `vary overa predetermined range in vwhich a `port .248 .insleevie |156 opens into an annular recess 250 in projection 225. lever 64 is advanced `clockwise throughout 1a :predetermined Vrange in reference :to the uniformly calibrated R. P. M. vscale f6.8., Fig. 1, 4the .deflection of spring 234 is varied :at a non-uniicrm rate so that the speed required to produce .a state of equilibrium .increases to the scale value corresponding to the position of the lever.

Recess 2.50 adjacent sleeve |56 is :connected .by a conduit 252 to a chamber 2,54 below ',overspeed power piston |52. 254 is controlled by a governor -valve .256 which cooperates with sleeve |56. Valve 256 has a .pinand-Slot connection with vgovernor lever '|44 and is slidably operable inside sleeve ,4.5.6 only response .to movement .of lever |44. The `governor valve is undercut to provide an annular chamber which vis connected through .a port .262 .in sleeve |56 with the upper end vof main fluid conduit v|64 `so that the annular chamber is maintained .at the pressure (p1)- 'The land .at the lower .end of valve 256 is the same width as port 254B so thai'l when valve 256 is zin its neutral position in respect to sleeve |56, as shown, port 243 Vis just covered.

The right-hand end of governor .lever :|44 .is hinged on .a pin 266 in projection 225 :and fits left-hand end is supported by rod 2|2. -Movement of the overspeed power piston |52 vand hence of rod 2|2, either upward or downward, .controls movement of governor lever |44 and governor valve 256. Whenever ythe end of the main floating lever |12 is engaged with the finger l21|), and push rod I |4 does not touch screw `2 I4, movement of piston |52 controls the position of lever .III 2 vindependently of cam |15, whereby ythe speed con-- trol system lis effective to modify the `Ifuel 'flow called for by the manual .control system. A spring 265 biases piston |52 downward 'in opposition to the pressure .diierential '(pz-pi so that there is a diilerent predetermined position -of piston |52 .corresponding vlto each value of the diierential. An -adjustingscrew 2f|| vis provided in support 266 for limiting upward movement of the right-hand end of lever H2, thereby limiting travel of piston |52 and vlinger 2|10. This establis-hes a minimum value :of 'the variable rcon-troll .Cam |56 is .generated 4so that as control The pressure A(pz) in chamber i I1.0 oil pressure (ne) inonder to avoid vburner Hblowout and .consequent .engine stoppage.

Coordination of the manual .and .speed control systems Both `cam 1| |6 .in vthe manual control system and cam 11250 -in fthe speed .control system .are fixed to contr-o1 shaft .60 for `simultaneous clockwise Aoperationzas control lever .64, Fig. l, is advanced clockwise lthrough .the predetermined range, In the :embodiment shown, .the total :range .of movement of ile-ver |54 is approximately 100.

In a'condition of steady-state operation at constant speed and :constant fuel flow, the positions ci -all :movable elements in both the lmanual and the speed control systems are fixed except in respect to rotation, -main servo valve |03 and governor valve 256 are in their neutral positions, pressures (p2) and (pc) .are substantially con- Ystarrt, and as subsequently explained .and as shown lin Fig. 2 main floating lever is Isupported by nger 210 so that there is a slight amountof clearance ybetween Arod H 4 and screw f2 i4 When control lever 164 `is advanced clockwise `Afrom the position vshown 'in'Fig l `to another nposition within the first 90 'range of movement .of `the lever, the lift-of cam |-6 decreases and pushrod 4H 4 is fur-ther separated from adiusting screw 2-|4, the y.main noating lever ||f2 'being .prevented from 'instantaneously following vthe epush rod by linger 2 I0 in the speed control system. Simultaneously with movement of =cam 6, however, cam

lili) also Aturns clockwise -to Lelevate push rod assembly 232 Aand to .thereby turn setting lever 48 .counterclockwise =on 'pin 230. The downward force of governor spring 234 thus increased and governor valve -s'leeve |56 is .depressed from its vneutral position in respect to valve 2.56 so that ilu-id `flows from conduit 252 through recess i250 and port 2148 into chamber |54, thereby decreasing .pressure (p29 in :conditi-H52 `and chamber 254. The overspeed power piston |52 and rod A2|2 .consequently 'move downward, .allowing mainiloating lever |2 to turn clockwise, `:thereby moving main servo :valve 4|68 .below its ,neutral position and producing increased ffuel ilow and engine Lspeed -as previously explained.

In addition to allowing the rightward /end olf lever l|f|2 :to descend, as explained above, ldownward movement :of rod 2f|2 and linger 2|=\'| simultaneously allows the left end of governor lever :|44 and hence governor valve :2.56 :to move `downward so as 2to reduce the Aeffective area of ilow from port r248 to chamber |54, :thereby retarding decrease of pressure `(per :and the resultant Vin- '.crease in the value-of fuellow.

The amount .of .clock-wise'movement .of lever 2| I2 about connection :|13 corresponding to downward movement of rod .212 'is limited lby push rod II-4. If the engine control 'lever iis advanced lsuficiently far :and/:or rapidly, rod Y2-l'2 quickly moves `downv:ward so that linger l2 |.0 is disengaged from lever ||2 when A'screw `214 .contacts push vrod .I I4 and downward `.movement of lever ||2 is thereby arrested. In this condition, the manually operated cam ||6 `determines the position of the Arightward end fof lever |112 and the speed control system becomes temporarily ineffective. The :fuel :flow to the engine corresponding :to a .given position of .the engine control lever is .thereby rendered maximum during acceleration of the (engine. The maximum fuel flow during periods :of acceleration is determined by l'the control lever setting acting through cam H6, and not by the-difference between yactual speed rand desired speed.

1l This limitation of the fuel ow during acceleration is necessary to prevent overheating of the engine.

As the engine speed approaches the value corresponding to the position of control lever 64, governor valve sleeve |56 rises so that when the engine speed has the desired value corresponding to the lever setting, port 248 is closed by the valve. When this occurs, screw 2|4 in lever H2 is again lifted slightly oi push rod ||4 by finger 2|0. During this process, the main power piston rises to a new position corresponding to the new position of rod 2 I2.

When control lever 64 is moved in a counterclockwise direction from one position to another in the 0-90 range of lever movement, reversal of the above process takes place. Simultaneously with upward movement of rod ||4, push rod assembly |46 is lowered so that setting lever |48 reduces the deflection and load of governor spring 234 and governor valve sleeve |56 rises to permit flow of uid at pressure (10,) from conduit |04, through port 262, past valve 256, through port 248 and recess 250 into conduit 252 and chamber 254. Pressure (p2) is thereby increased and the overspeed power piston rises. Although elevation of push rod ||4 by cam ||6 tends to reduce clearance between screw 2|4 and rod H4, this clearance is increased in response to the upward movement of rod 2|2 and nger 2|0, the amount .of clearance between screw 2 |4 and rod I4 being vgreatest when the amount of engine overspeeding is greatest in respect to the new lower desired value of speed corresponding to the new lever position. In other words, during deceleration the .speed control system determines the fuel ilow. .Maximum deceleration is limited by stop 2||. The fuel flow decreases owing tocounterclockwise movement of lever ||2 as explained heretofore, and as the engine decelerates, the clearance between push rod |4 and screw 2 |4 is reduced to a new value which remains substantially constant when equilibrium of the combined manual and speed control systems is restored.

With the position of control lever 64 fixed, the `engine speed may vary owing to variations in fuel quality, combustion temperatures, or other factors over which the barometric'or thermal control systemsmay or may not have control.

When, under such circumstances, the engine speed increasesv without any change in position of control lever 64, sleeve |56 is raised from its neutral position in respect to valve 256 and, as previously shown, pressure (p2) is thereby increased. The overspeed power piston rises and the process of reducing the variable control oil .pressure (pc), the fuel ow, and hence the engine speed, follows, until the desired Value of speed is restored. When the engine speed decreases at a fixed position of the control lever, the process of increasing the fuel flow to restore the desired value of engine speed is substantially the reverse of the process which occurs upon overspeeding.

As control lever 64 is moved between ts90 and 100 quadrant positions, the lift of cam |50 remains substantially constant at a maximum value. The engine speed therefore has a substantially constant maximum value when the lever is in its 90-100 range of travel. Within this range, however, the lift'of cam IIS continues to increase to a maxium value corresponding to the extreme or 100 position of lever travel. Response of the combined manual and speed control systems to movement of the control lever in this .ten-degree rangeis similar to that in cases previously explained in which the-fuel flow and engine speed vary as a function of both the manual and speed control systems, except that the speed control system is effective to override the manual control system to a relatively greater extent in order to maintain a substantially constant maximum value of speed. As the fuel flow is increased at constant maximum engine speed, the engine torque and hence the brake-horsepower increase, the maximum brake-horsepower being developed at the lever position. The adjusting screw 246 may be set to cause actuation of spring 240, if desired, at any position of cam |50, and to thereby establish the maximum speed at a lower value than is otherwise obtainable as a function of the lift of the cam. Alternatively, if desired, the lift of cam |50 may be allowed to increase throughout the 100 range of lever movement.

Barc/metric control system The operation of lever mechanism 32 and positioning bar 286 and their relation to rod |62 is explained in the following description of the barometric control system and in subsequent explanations of coordinated functions of the barometric and other component systems.

In the barometric control system, the upper end of bellows |34 is fixed inside casing 'i2 directly over bellows |36 which is of substantially the same effective area and which has its lower end fixed to a portion of wall |64. A bar 263 rigidly connects the free ends of the bellows to each other so that expansionl or contraction of either is accompanied by an equal and opposite movement of the other. A cylindrical stop 26S is provided to limit contraction of bellows |36. Inside bellows |34 and at its upper end there is an adjustable spring support 2'10 the position of which can be varied as desired by means of a nut 212. Between the lower end of support 220 and the upper end of bar 263 there is a tension spring 214 for biasing the bellows and bar assembly upward in opposition to the differential (pn-pr). A cover 276 and a gasket 218 are provided for enclosing support 210 and nut 212 which, upon removal of cover 276, are accessible from the exterior of the casing. The barometric lever. |28 is hinged at approximately the mid- `position of its length on a pin 336 in bar 263, the

left end of the leverbeing connected to the upper end of barometric valve |24 by means of a pinand-slot connection 286 which permits vertical movement of valve |24 in sleeve |25 as the angular position of lever |28 changes. The right- .hand end of lever |28 has a pin-and-slot connection with a rod 282 fixed to the barometric .power piston |26. The upper end of rod 282 above its connection with lever |28 is hinged to a link 284 which is pivotally connected to the left end of positioning bar 286 by means of a pin 28% on which turns a roller 290 engaged with the fixed barometric cam |30. The position of cam |30 is xed by a pair of pins 292 and 204 respectively tted into xed supports 296 and 202. The cam is slidable on the pins so that it can be removed from the apparatus for replacement or any other desired purpose. The right-hand end of positioning bar 286 has a pin 298 fixed therein on which the circular bearing 208 is mounted. Roller 290 is held in contact with the upper surface of cam |30 by means of another roller 300 which is rotatable on a pin 302 fixed in a triangular bracket 304. Bracket 304 is pivoted toY link 284 and a spring 306, compressed between the link and one side of the bracket, holds roller 30|)V 'against the lower side of .cam |30..` as 282 moves ina vertical direction. link 2,841fo11ows so that roller 260 remains engagement Vwith the contoured upper ,face of .cam |30. `Both ver.- tical and angular movement are imparted to link 284 in this process so that, when piston A26 and rod 282 descend, bearing 208 :is inoved .letward .and the downward force on .main power piston due to spring 204 is increased; and, similarly, when piston |26 and rod 282 rise, bearing 20,8 is moved rightward .and the downward torce on .the main power piston |10 is decreased.

The barometric servo valve |24 is undercut .to provide a pair o f annular .chambers `30.18 and :31.0 between the valve and sleeve .|25 in `which :the valve is slidable. The vertical position lof Naive sleeve |25 in reference to casing 'I2 is fixed and the sleeve is rotated by means of a gear 312 .dri-.ven from kshaft through a suitable connection (not shown) The valve sleeve has three pairs .of ports .332, v334., .and 33|.

In all operating positions .of valve |24, lports 331 .open into the annular chamber 308 and .ports .334 open into the annular chamber 13|0. Fluid in chambers 338 and 310 is maintained vat .pressures .designated (be) and (p4), respectively, ,as later explained.

Ports 332 are just closed when valve |24 is in its neutral position, as shown in the drawing, ythe width of the ports being substantially equal to .the `.width .of the valve land between .the lower end of .chamber 308 and the upper end of chamiber 3|0. The outlet passage .|30 in sleeve |25 is also just .closed by the land at the lower end of the valve and routlet passage |40 is similarly `iust closed .by the land at the upper end of .the valve, when the latter is in its neutral position.

Ports 332 are connected to the end of conduit |06 so that the ports 332 are continuously supplied with uid at .pressure (p1). Ports 3.3.4 are connected to one end of .a conduit 322 which has its other end connected to an expansible chamber 324 below piston |26. Rorts .33| are connected to a pair .of .conduits 326 and .328. Conduit 328 is connected to a check valve chamber 338 in wall |64 above the barometric power `piston |26, for transmitting vthe pressure (p3) to chamber 330 from chamber 308. Conduit `328 is supplied with uid from chamber 308 at pressure (p3) and is intermittently .connected by .means of a slot 340 on main drive shaft 58 to -a conduit 338 for supplying fluid at a pressure (p4) .to .a chamber 32? above piston |26. Slot 340 inter.- mittently connects conduits 326 and 328 as it rotates and is descriptively referred to as a chopper valve. It serves to restrict ow between conduits 326 and 328. The area of slot 340 is substantially greater than that of an equivalent iixed restriction between the two conduits. A number of parallel slots may be substituted for the single slot 340, if desired.

When the barometric servo valve |24 is elevated above its neutral position, uid is permitted to flow from annular chamber 308 through outlet |46 to reservoir '|4, thereby reducing the pressure (p3) in conduits 328 and 328. Simultaneously, fluid is permitted to iiow .from conduit |06 through port 332, chamber 3|0, and conduit 322 to chamber 324, thereby increasing the pressure (p5) in chamber 324.

When valve |24 is depressed below its neutral position, fluid is permitted to flow from conduit |06 through port 332, and chamber 308, to conduits 320 and 328, thereby increasing the .pressure (ps) .in conduits 326 and 328. Simultaneously,

'fiuid owsrromchamber 318 through outlet 1.38

to reservoir 1.4., thereby reducing the value of pressure (p5) in ,conduit322 and chamber 324.

The position of 110411268 and hence the position of pin .336 :is determined Eby the pressure difier- .entiai ipp-#10%) acting on .bellows |34 and -|36 and by spring 214, there being a .diierent predetermined position .of the pin for each value ofthe diterental. at any given xed position of spring support 210. In .steady state operation. when the barometric servo valve .is in its neutral posiation, .asshown the positions of the .power piston |26 .and of rod 28,2 .are predetermined by the vposition of fulcrum pin 336 and the pressure difierential (pe-m) yacting on piston |26. This difterential has a substantially constant value when the barometric .control system is in equilbrium. and equals Zero when the apparatus is constructed so that no force is required to maintain :bearing .208 in any xed position corresponding to a fixed position of pin 33,6.

The barometric control ,system varies .the .position of power piston |26 and rod 282 toymantain Servo valve |24y-in :its neutral position as the position of fulcrum pin 336 changes in response to changes in .the value of `the dinerential 12b-pg). The ba-rometric control system therefore .positions vbearing 20.8 .as a .function .of .the :barometric .pressure diierential. The power for Apositioning bearing 20.8 :is supplied .by the hydraulic system. The downward load von .main power piston ||0 dueto spring 204 .is therefore modified in accordance with the barometric pressure 4diierential.

Chamber ,321 is .connected to .check valve chamber 3.30 .by a conduit 342 for flow from chamber 321, past a ball check valve 344 into chamber 330, when the pressure (p4) .exceeds pressure (p3) in chamber .33.0 by a small amount predetermined by a spring 346 which loads the valve. The .check valve prevents reverse flow! from .chamber :330 to conduit `342 at all times.

Considering the barometric control vsystem independently of the manual control Vand .other component .control systems, when a .conditionof equilibrium is disturbed by 4an increase'in com.- pressordischarge pressure (10D) .or a decrease in compressor inlet pressure .(pE), and hence .when the differential (pD-pE) increases, bar 268 and vfulcrum pin 336 are lowered to a new posit-ion. The rightward end of barometric floating lever |28 is not aifected until pressure changes produced by the valve cause movementV of piston |26. Downward movement of lpin 336 causes downward lmovement of the servol valve |24 and consequent increase of pressure (po) in chamber 308 and conduit 328 and 326 as previously explained, and also decrease of pressure (pt) in chamber 3|0, conduit 322, and chamberv 324 .below power piston |26. Increase of pressure (p3) in conduit 326 produces a flow through chopper valve 34.0, resulting in a .corresponding increase in pressure (p4) in chamber 3.21 above the power piston. The rate of change of pressure (p4) is a function of chopper valve 340. As the difierential increases, the .barometric power piston |26 moves downward, thereby turning lever |28 clockwise lon fulcrum pin 336 and moving servo valve |24 upwards toward its neutral position. The downward lmovement .of piston |26 and rod 282 continues until the neutral position of valve |24 is restored and rod 282 is in a new position corresponding to the neutral position of the valve and the new lower fixed position of pin 336,

''Whe equilibrium occurs, pressures .(pi). and (p5) :are again substantiallyconstant. v

In the above train of events,= the particular Yvalue acquired by .the differentiall (p4-p5) in restoring valve |24 to its neutral position is. not 5 important, since all that is required is thatthe position of rod 282 corresponds to the neutral po.- sition of the valve. If movement of rod 282 is yopposed by frictional or other forces, the control Aoperates to vary the 'differential (p4-p5) sufficientlyto compensate such forces. process, check valve 344 remains seated, sinceV the io During the pressure (p4) cannot increase above the pressure (p3).

When the compressor pressure dierential (pn-11E) decreases, with the barometric control rsystem in an initial state of equilibrium, bar 268 and pin 336 rise causing clockwise movement of lever' |28 -about its pivotal connection with rod '282.and raising the servo valve |24 above its 0 neutral position. As previously explained, pressures (p3) and (p4) decrease and pressure (p5) increases, thereby causing piston |26, rod 282, and the right-hand end of lever |28 to move I l upwardly so that the servo valve moves downg5 ward toward its neutral position. During this y338 through chopper valve 340. Hencevrod 282 moves upwardly (in a fuel flow decreasing direction) more rapidly than it moves downwardly (in a fuel ow increasing direction). Equilibri- 3 um of the barometric control system is restored with valve |24 in its neutral position, with fulcrum pin 336 in a new higher fixed position, with rod 282 in a corresponding new higher fixed position in which the upward and downward forces fig@ on the rod are in equilibrium, and with check valve 344 again seated. As is apparent from the drawing, when movement of fulcrum pin 336 displaces the barometric servo valve |24 in either direction from its neutral position, the baro- Eug metric power piston |26 is required to vmove approximately twice as far in the same direction to restore the valve to its neutral position.

Coordination of the manual, speed, and baro- (go metric control systems The manual, speed, and barometric control systems cooperate to regulate the fuel flow and engine speed as a function of manual control, pspeed, and the compressor pressure differential (pD-pE) The operation of the combined manual and speed control systems were previously explained on the assumption of a xed position of circular bearing 208 in lever mechanism |32.,f.(',= The barometric control system varies the posio tion of bearing 208, thereby varying the down- Ward force on main power piston H0 and hence varying the value of the variable control oil pressure (pc) in chamber |90 and conduits |22,l and 56.

As bearing 208 moves leftward, corresponding to downward movement of the barometric power piston |26 produced by an increase of the compressor pressure differential (pD-pE), the force transmitted by the bearing from spring 204 and lever |98 to lever |94 and rod |92 is increased so that the value of pressure (pc) corresponding to the position of main control shaft 60 increases.

=Conversely, as bearing 208 moves rightward, cor- 75 'responding' to decrease. of the 1`differential (pn-12E), the pressure (pc) decreases.y

It is thus seen that the value of the lvariable control oil pressure (pc) corresponding Lto any givenl position of the manual control lever 64, Fig. 1, depends upon the barometric control system, the pressure (pc) increasing as the differential (pn-12E) increases, as when the engine speed increases, the speed of flight increases, or as the altitude of ight decreases.

Since the compressor pressure differential increases as the engine speed increases, it follows that the barometric control system controls the rate of acceleration when the engine control lever is advanced. On movement of the lever, within the rst 90 range of operation, from one position to another corresponding to a higher rate of speed, the initial valuev of the pressure (pc) corresponds to the initial value of the differential (p-11E) and to the initial' lever position.V The increase of pressure (pc) due to movement of the manual control isrelatively rapid, but the corresponding increase due to increase of the dfferential (pn-pla) occurs only as the engine speed increases and as the barometric control system responds to such speed increase. The barometric control system thus serves to control acceleration and deceleration of the engine.

When the entering air density increases as a function of speed and altitude of flight, bearing 208 moves leftward to increase the pressure (pc) and the fuel iiow as above explained. Conversely. as the flight speed decreases and the altitude increases, the differential (pn-10E) decreases and bearing 208 moves rightward to decrease the pressure (pc). The barometric control is sometimes descriptively referred to as the altitude control, and cam |30 is customarily contoured with closer regard to altitude compensation than to acceleration control, particularly since the latter is accomplished to some extent by chopper valve 340.

The contour of the barometric cam |30 is made to.provide a desired position of bearing 208 for every value of the compressor pressure differential. In steady state operation, in which the temperature control system is ineffective and the control apparatus is in equilibrium, the fuel ow is dependent upon: (l), the manual and barometric control systems; and, (2), the speed control system which overrides these combined systems to reduce the fuel flow, as previously explained.

Thermal control system The thermal control system is essentially a means for overriding the manual control system to reduce the fuel flow and engine speed when a predetermined limiting value of temperature is exceeded.

Thermal control 10, as shown, includes a body 348 on which is fixed a thin walled tube 350 which has its right-hand end closed. Body 348 is provided with a pair of chambers 352 and 354 separated by an apertured wall 356 `and connected to conduits |62 and |60, respectively. A rod 358 is xed to the closed right-hand end of tube 350 and is slidably operable in the apertured end of body 348 on which tube 350 is assembled. The left-hand end of rod 358 is contoured as a valve 360 which is normally seated in wall 356 to prevent fow from chamber 354 to chamber 352.

'Tubev 350 and rod 358 are made from materials having substantially different coefficients of thermalexpansion, so that when the tube and vrod vare heated, the tube expands faster than the rod, the thermal control generallybeing made so that the valve remains closed until the predetermined limiting temperature is exceeded. The control is installed with tube 355 exposed to the engine temperature, as in the tail pipe 30 of the engine of Fig. l. Then, when the tail pipe temperature exceeds the limiting value, the valve opens to permit flow from conduit |50 through chamber 354, past valve 355, into chamber 352, and through conduit |52 to reservoir 14. `The pressure (p6) in conduit |60 is decreased as valve 365 opens.

The thermal piston |55 functions `as a chopper valve similar to chopper valve 340 in the barometric control system. vIt consists of Aa generally cylindrical center portion operable vin an apertured portion of wall |64 by means of a shaft 362 which is rotated concurrently with shaft |1|. A push rod 354 is attached to the upper end of the piston and extends through wall lH54 for engagement, under conditions to be specified, with a finger 335 fixed to push rod I4. A chamber 363 is provided above piston |55, and the latter is biased upwardly by a spring 310. Piston |55 is provided with a slot 312 so that when the piston is rotated chamber 358 is intermittently connected through slot 312 to the upper end of conduit |51 leading to main uid conduit |56 and to one end of conduit 314, the other end of which is normally clesed by push rod 238.

When valve 365 in thermal control 10 is closed, the pressure in chamber 354 is maintained at pressure (p1), as in conduit |51, and piston |55 is held downward so that push rod 354 does not contact linger 366. When the limiting engine temperature is exceeded, however, valve 360 opens and fluid is drained from chamber 358, the pressure therein thereby being reduced owing to a drop across slot 312, so spring 310 forces valve |55 upwards and causes push rod 364 to engage finger 36S, causing the latter to rise and to move the main oating lever in a counterclockwise vor fuel flow decreasing direction. A decrease of the value of pressure (pc) results and the fuel flow and engine speed are decreased below the values corresponding to the manual control setting. The flow remains at its decreased rate until the engine temperature is reduced to or slightly below the limiting value, whereupon thermal control valve 35@ closes, valve |55 moves downward, and normal operation is resumed.

The thermal control used in the fuel control apparatus need not necessarily be the particular type shown since any temperature responsive device functionally equivalent to control 10 may be employed if desired.

Provision is made for resetting the thermal control system, as follows:

Fluid may be supplied at pressure (pi) to conduit 314 from a conduit 31B which is connected to conduit |66. This supply is controlled by an annular groove 313 in a portion of rod 238 which is guided by a portion 319 of casing 12. The ends of conduits 31B and 314 enter portion 31.9 of casing 12 and are separated from each other by..rod 238 when the position of cam |50 corresponds to any position of the engine control lever ina preselected range of movement of lever 64, which may, for example, be the -90 range. When the control lever is further advanced, however, the lift of cam |53 increases so that conduit 3111 is opened through groove 318 to conduit 3176. At normal engine temperatures, no flow occurs past groove 318 since the same pressure (p1) exists on both sides of it. However, when the .limiting engine temperature is-exceeded and thermal-con trol valve 355 opens, chopper valve |55 is supplied with fluid at pressure (p1) by both conduits |51 and 31d, andthe pressure in chamber 368 -corresponding to any opening past valve :360 is greater than in the previously explained case Vin which conduit 31d was closed by rod 238.

Thus, while the action of thermal control 10 'is always the same in respect to temperature and rate of valve opening, the response of thermal piston i is less rapid when the control lever is in its last ten degree or other desired range vof travel, in which the engine speedsetting remains constant and the fuel flow is manually variable to vary the engine power.

The two kinds of thermal override control .are sometimes referred toas applying to normal and emergency operation, respectively. Thus, when the lever is advanced in the -100 range to increase the fuel flow to obtain increased or emergency power, thermal override is desired .to occur less rapidly and at a higher value vof temperature than in normal operation in the 0-90 range of control lever travel.

The manner in which the manual Vand barometric control systems are coordinated in order to control the pressure (pc) and the fuel flow as joint functions of the enginecontrollever and the compressor pressure differential is apparent from the foregoing. The speed and -thermal control systems are shown to nbe override controls for preventing excessive engine speed and temperature.

Figure 3 Referring to Fig. 3 of the drawing, lthere is shown a cross-sectional view of the apparatusof Fig. 2 substantially as built. Those elements in Figs. 3 to 8 which exactly correspond to their counterparts in Fig. 2 have been giventhesame reference numerals and will not be individually described in connection with the Figs. 3 `to 18.

The path of fluid flow Ain the apparatus of Figs. 3 to 8 is substantially the same in all functional aspects as that previously described in connection with Fig. 2; the particular sectionsof Figs. 3 to 8, however, are not adequately illustrative of the conduits and/or passages corresponding to those shown somewhat diagrammatically but nevertheless completely in Fig. 2. In -description of Figs. 3 to 8, therefore, reference to many structural details of fluid flow paths Vare necessarily omitted.

The embodiment of Fig. 3 includes four major castings; namely, a ange casting 330, a base 382, a bracket 333, and a cover 38e arranged in the stated order. Base 332 is separably fastened to flange casting 383; bracket 383 is correspondingly separably fastened to base 332; and cover 33 is also separably fastened to base 332 forenclosing the bracket and its corresponding assembly subsequently specified. A major portion of the working parts of the apparatussubject-to adjustment and inspection or other voperations during calibration, test, and service are rendered easily accessible by removal of cover 334. Suitable vgaskets are placed between `the lcontacting surfaces of the flange casting, base and cover. The vertical centerline of the assembly Vis substantially coincidental with vthe respective centerlines of the flange, base, and cover castings, ,each of which is substantially symmetrical in respect to itsvcenterline.

Flange casting 33B is provided withja number of holes 399 through which screws may be inserted to fasten the ilange casting to the engine. A spline 392 adapted to engage a corresponding driving mechanism in the engine is located at the lower end of the main drive shaft 58 which extends slightly below the ilange casting and has its upper end approximately ush with the upperV side of the flange casting. The drive shaft is keyed to a gear 364 in iiuid pump 82 for operation of the pump, the shaft being guided by a pump housing 396 and a pump end cap 398. The only other principal member of the pump is a rotor 408. A gear 462 is keyed to the upper end of shaft 56 for rotating a gear 463 attached to the thermal piston |55 (see Fig. 7), gear 402 performing part of the function of the gearing |12 in Fig. 2. A drive shaft seal 404 and a seal plate 406 are included in the assembly for preventing leakage of fluid from the apparatus.

The base casting 382 is provided with a centrally located bearing 408 in which a shaft 4|6 operates as an extension of the main drive shaft 58. The lower end of shaft 4|() is notched to provide a driving engagement with the toothed upper end of shaft 58 when base 362 is assembled to flange 380, as shown; but the base and ange may be separated without removal of either shaft from its corresponding casting assembly. A gear 4|2 is fixed to the lower end of shaft 418 and drives a gear train including gears 496, 3|4, and 4|4, as shown in Fig. 5. Gear 414 is fixed to a third gear 416 and both rotate freely on shafi-I 4|0. Gear 4|6 drives a gear 4|8 shown in Fig. 4.

Overspeed power piston |52 operates in a sleeve 420 retained in base 382 by a plate, the piston being biased downward by spring 265 in opposition to the pressure (pz) in chamber 254 below the piston. Rod 2|2 extends upward from piston |52 to engage the governor lever |44.

Base 382 also houses bellows |36 the lower end of which is fixed to an apertured plate 424 assembled into the base in line with a passage 42E-in flange casting 386 for supplying air at the compressor entrance air pressure (E) to the bellows interior. Passage 426 corresponds to conduit 54 of Fig. 1 and has its outer end threaded for the connection thereto of a suitable fluid pressure transmitting line.

The base casting 382 is provided with a number of studs 385 (see Fig. 6) over which bracket 383 is placed for assembly with the base by means of nuts 381 which are accessible on removal of cover 384. The bracket 363 supports all other elements of the apparatus except an adjusting sleeve 430 attached to the upper end of cover 384. The cover is removable from base casting 382 Without disturbing adjustment of the apparatus and substantially all of the working elements are thereby rendered easily acccessible for inspection, adjustment, parts replacement, and similar purposes.

Bellows |34 has a flanged fitting 432 at its upper end whichis retained in the upper portion of bracket 383 and locked in place by means of a lock nut 434. Spring 214, supportJ 216, nut 272, and cover 216 are provided as in Fig. 2, excepting that in the apparatus of Fig. 3, cover 216 is not accessible from the exterior of the completely assembled apparatus and' therefore is not subject to tampering. A plug 436 is threadedly inserted in a collar 431 attached to the lower end of bellows |34. The spring 214 has its lower end hooked into an eye on the plug 436 and its upper end 20 hooked into an eye formed on the lower end of support 218. The plug 436 has a hexagonal portion formed integrally with it so that it may be readily removed.

With this construction it is possible to change bellows springs quickly, if desired. The nut 212 is removed, and plug 436 is removed. rI'he spring 214 and support 218 come out with the plug 436. The spring may then be changed and the device reassembled. A plug 438 at the upper end of bellows |36 is connected to plug 436 by means of a threaded rod 440, which may, as shown, be formed integrally with plug 436 and which corresponds to rod 268 of Fig. 2. An adjustable nut 442 is threaded onto connection 446 and locked in a desired position on the connection by means of 'a locknut 444. The barometric floating lever |28 has an opening 446 through which nut 442 is assembled on connection 448. The lever is provided with a pair of pins 446 which engage in nut 442 thereby causing the latter to serve as a fulcrum for the barometric floating lever.

The upper end of shaft 416 is iixed to a revolving plate 456 in the speed responsive device 224, which includes a pair of fly weights 452 and a casing 454. `Operation of device 224 is the same in Fig. 3 as in Fig. 2, the device controlling the position of the governor valve sleeve |56 which operates in a ported guide 455 pressed into a portion of bracket 383. A governor valve 456 performs the function of valve 256 of Fig. 2, but differs from valve 256 in that instead of a pin-and-slot connection with governor lever |44, valve 456 is provided with a fulcrum 458. A light spring 46o is compressed between the upper end of valve 456 and a stop 462, for maintaining fulcrum 468 in engagement with governor lever 456. Stop 462 is threaded into the uppermost portion of bracket 333 and is used as a guide for retainer 236 and for limiting downward travel of setting lever |49. In this respect, stop 4162 corresponds to adjusting screw 24-6 of Fig. 2. The upper end of adjusting sleeve 430 extends outside cover 384 and is rotatable therein; the sleeve is fastened by means of a lock nut 464 in a position corresponding to the desired vertical position of stop 462. The lower end of sleeve 430 is slotted for engagement with a pin 466 diametrically inserted in the upper end of stop 462, which moves vertically in response to rotation of the sleeve.

The interior of cover 384 and openings in base and flange castings 362 and 366 comprise the reservoir 14, as shown in Fig. l. All gears, levers, pivots, bearings, and other working elements, not otherwise lubricated in the process of fluid pressure control, operate in a continuous oil bath. The reservoir is vented similarly to the reservoir of Fig. 2, and the apparatus may be operated as a closed system or be connected to the engine oil supply system as in Fig. 2.

Figure 4 Referring to the drawing, Fig. 4, there is shown another cross-sectional View of the apparatus of Fig. 2 substantially as built, corresponding to the View of Fig. 3 except for omission of the flange casting 380.

In base casting 382 is shown the main power piston l I6 operable in a guide 468. A bearing 416 is assembled at the lower inside end of piston |16 for engaging the push rodl92. Rod |92 is connected to main floating lever H2 and the lever 412 which ispivotedon a pin 414 in bracket 383, corresponding to'lever |94 and its pivotal con- 21 nection with support |96,in Figure2. 'I'hepo'wer piston I I yis rotated by gear |74 andthe 'Varlable control oil pressure (pc) 'is transmitted to the pump delivery varying means 46 of Fig. 1 from the chamber |90 below the piston.

Also assembled in base 382 are the main servo valve |08, main servo valve sleeve |09, and gear 4|3 which is driven by gear 4|6 of Fig. 3. Sleeve |09 rotates in a bushing 411 pressed into the base casting. Valve |08 has a pin-and-slot connection 476 with lever I I2. Spring 2| 8 is compressed between the upper end of valve |08 and a portion 220 of bracket 383. Adjusting yscrew 2|4 is Xed in lever I I2 bymeans of lock nut 2 I5, the lower end of screw 2 I4 Vengaging a finger 365 on the manually operated push rod I I4 of Fig. 2. Finger 2|0 is shown in Contact with lever I'I2, the iinger being operated by the rod 2|2 and overspeed power piston |52 of Figs. 2 and 3.A

The barometric power piston |25 operates in a bushing 480 retained in base 382 by means of a plate 482 for sealing rod 282 which has a pivotal connection indicated at 484 with the barometric lever |28.

Elements of lever mechanism |32 are substantially as shown in Fig. 2, including barometric cam |35, fixed on pins 292 and 254, roller 290 and pin 228, positioning bar 286, circular bearing 208, pin 298, and lever |98. The upper` end of spring 204 is hooked into the lower end of an adjusting screw 486 and its lower end is anchored in a pin 488 retained by the base casting 382. Screw 486 is slotted at 481 to receive a pin 485 carried by a pair of bearings 49| at the opposite sides oi the end of lever |98. An adjusting nut 453 threaded on screw 486 serves to adjust the tension of spring 264. Nut 493 isheld by a lock nut 495.

Cover 354 is fastened to the base casting 332 by means of a number of screws 490.

Figure 5 Referring to Fig. '5, there is `shown another cross-sectional view of the apparatus of Figs. 3 and 4. The additional parts ,shown in Fig. 5 are as follows: barometric valve |24, barometric lever |28, barometric valve sleeve |25 rotatable in a bushing 492 retained in base 382, gears SI2 and 3| 4, and a shaft-494 for supporting gears 3|@ and 455, respectively.

There are also shown the control shaft 60 having a splined end for attaching a lever thereto, cams H5 and |50 adjacently fixed to shaft 60, push rod I I4 operated by cam I I6, a light spring 458 for maintaining rod |I4 in contact with cam H5, finger 3516, governor push rod assembly |46, and undercut portion 318 of push rod 238.

As previously explained in connection with Fig. 3, adjustable stop 462 is employed to limit the deflection of spring 234 at a maximum value; similarly, an adjusting screw 461 is provided to Vlimit the deflection of the spring at a minimum value for idling. Another adjusting screw 469 is provided in the right-hand end of lever |48 for compensating tolerances in manufacture and assembly of the push rod assembly |46 and cam |50.

Figure 6 Referring to the drawing, Fig. 6, there is shown a section through the controlapparatus of Figs. 3,

4 and 5, as indicated by section line '3-3 on Fig. 3. Theprincipal purpose of Fig. 6 is fto-indi cate locations of sections V3-3, 4-v-4. and 5--5 corresponding to Figs. 3, l4 and 5, respectively.

22 FFzgures 17 dnd 8 There .is shown in '.these "figures the vthermal piston |55 and its .related mechanism. .Piston |55 is rotated by .gear 403 attached toits lower end and driven by gearv402..

Gear 403 and piston |55 are `supported by a combined thrust and radial bearing 500, which rests in a retainer 502 for the upper `end of .a spring 504, Whose bottom Yend engages a suitable guide 506 in a recess inthe flange casting 360. Spring y504 corresponds to spring 310 of Fig. 2.

Piston |55 rotates in a Ycup 508 which is retained .in a recess in the base casting -382 by means of a suitable retainer plate 5|0. Cup 508 is provided with outlet ports 5| 2 which communicate with the conduit |50 of Fig. 2, and with inlet ports 5|3 and 5| 4 which communicate rrespectively with conduits |5'I `and 314 -of Fig. 2. 0 rings 509v and 5|I are provided in grooves on the external surface of cup 508 to prevent leakage between inlet and outlet ports. .Athrust bearing 5||i is provided between the piston .|55 and the closed end of cup 508.

Push rod 364, which, as shown, may be formed integrally with piston |55, extends upwardly through base casting 38,2 and into -engagement with an adjustingr screw 5| 8 carried by linger 356 and locked thereto by a vlock nut 520. Finger 366 is carried by rod I4, which-extends upwardly through a port of -bracket383 l(see Fig. 5).

When cover 384 is removed, adjusting screw 5|8 and lock nut 520 arefboth ,readily accessible from the side foradjustment-purposes.

The terms and expressions `used herein are employed for purposes of description and not of limitation, and I have-no intention, in the use of such terms and expressions, of vexcluding any equivalents of the features shown and described or portions thereof, but .recognize that various modifications are possible withinzthescope of the invention claimed.

I claim as my invention:

l. Speed control apparatus for a turbojet engine Vhaving a fuel pump with means, responsive to a fluid control pressure, for varying its delivery of fuel to said engine, comprising: -a source of control fluid and conduitmeans -for the flow of said fluid from said source tosaid-:delivery varying means; a valve guide insaid vconduit means and a valve operable therein for regulating said control pressure in a portion .of said `conduit means continuously connected to said valve guide, said valve having a neutral Vposition wherein said regulated pressure has a Asubstantially constant value and being effective Whendisplaced in .opposite directions from said neutral position to produce opposite changes .in the value .of said regulated pressure; a cylinder communicating with said portion of said conduit means and a piston operable in said cylinder; loading means connected to said piston, vincluding means for applying to said piston a vforce which varies with the speed of said engine, `for controlling the position of said piston in accordance with a selected function of said regulated pressure; means for varying said regulated pressure in accordance with the movement of said piston, means for vapplying said regulated pressure directly to said delivery varying means, whereby said delivery varying means is actuated directly by said regulated pressure; a connection kbetween said valve and said piston for controlling the'jposition of piston, said pistonA being 'eiectivewhensaid valve 23y is displaced from 'said neutral position to operate said connection in a sense to restore said valve to said neutral position; and driving means for producing proportionate rotary motion of said valve and said piston to prevent sticking of said valve in its guide and said piston in its cylinder.

2. Speed control apparatus for a turbojet engine as set forth in claim 1, including manual control means, connected to said loading means, for displacing said valve from said neutral position to selectively vary said selected function, whereby said regulated pressure and hence the position of said piston are selectively varied by operation of said manual control means.

3. Speed control apparatus for a turbojet engine as set forth in claim 2, including means, controlled by said manual means, for modifying said loading force to modify said selected function, whereby said regulated pressure and hence the position of said piston are selectively varied by the operation of said modifying means.

4. Fuel control apparatus for an internal com-v bustion engine having a pump associated therewith for the iiow of fuel thereto, said pump having delivery varying means connected thereto, comprising: a source of hydraulic fluid at superatmospheric pressure, conduit means for the flow of fluid from said source to said delivery varying means, a valve guide and a valve slidable and rotatable therein for varying a control pressure in a portion of said conduit means, said valve having a neutral position wherein said control pressure is substantially constant and being effective when moved in opposite directions from said neutral position to produce opposite changes in the value of said control pressure, said delivery varying means being actuated by the direct application thereto of said control pressure; first and second levers movable on first and second fixed pivots respectively, a connection between said levers for transmitting the movement of each of said levers at said connection to the other of said levers, a spring having one end xed and its other end engaged with said rst lever for opposing movement thereof by said second lever, means responsive to said control Pressure for operating said second lever to transmit a first force proportional to said control pressure to said connection in opposition to a second force proportional to the load on said spring, means connecting said valve to said pressure responsive means for concurrent movement therewith, said pressure responsive means being movable to maintain said rst and second forces in equilibrium and being effective when said valve ldeviates from said neutral position to operate said connecting means in a sense to restore said valve to said neutral position; and rotating means for producing relative rotary motion between said valve and said guide to prevent sticking of said valve, whereby said control pressure has a value proportional to said load on said spring and whereby said fuel flow is a function of said spring load and said two force proportionalities.

5. Control apparatus as set forth in claim 4, wherein said pressure responsive means includes a piston guide and a piston responsive to said control pressure slidable in said piston guide, and including means connected to said rotating means for proportioned rotary motion between said piston and said valve to prevent sticking of said piston in its guide.

6. Control apparatus as set forth in claim 4, including a second valve guide and a second valve slidable and rotatable therein for controlling a second pressurek in a secondportion of said conduit means, operating means responsive to said second pressure for varying the position oi said connection to modify said two force proportionalities, and means connected to said rotating means for producing proportional rotary motion between said first and second valve to prevent sticking of said second valve in its guide, whereby said fuel iiow is varied by operation of said second valve.

7. Control apparatus as set forth in claim 6, wherein said operating means includes positioning means responsive to said pressure in said second portion of said conduit means for controlling said connection, a cam separate from said levers, and spring means for guiding a portion of said positioning means on a contoured portion of said cam to control the movement of said connection as a function of said contour.

8. Control apparatus as set forth in claim 4, including a second valve guide and a second valve slidable therein for controlling respectively second and third pressures in second and third portions of said conduit means, means for producing a fourth pressure Vas a predetermined function of said third pressure in respect to time, operating means responsive to the differential between said second and said fourth pressures for varying the position of said connection to vary said two force proportionalities, a cam separate from said levers for modifying the movement of said connection by said operating means as a function of the contour of said cam, and means connected to said rotating means for proportioned rotary motion between said first and second valves to prevent sticking of said second valve in its guide, whereby said fuel flow is varied by operation of said second valve.

9. Control apparatus as set forth in claim 4, including operating means, controlled by a manual means, for varying the position of said connection to modify said two force proportionalities, a piston guide in said pressure responsive means and a piston responsive to said control pressure and slidable in said piston guide, a second manually operated means for displacing said valve from said neutral position to vary the position of said pressure responsive means corresponding to said neutral position, thermal control means responsive to a temperature in said engine for overriding both of said manually operated means in a sense to decrease said control pressure when a predetermined value of temperature is exceeded, means for varying said predetermined value of said temperature, and means connected to said rotating means for producing relative rotary motion between said piston and said piston guide to prevent sticking of said piston, whereby said control pressure is varied by said operating means and both of said manually operated means. v

l0. Control apparatus as set forth in claim 9, including a drive shaft operated at a speed proportional to the speed of said engine, governor means responsive to Said shaft speed for overriding said second manually operated means t0 operate said valve in a sense to decrease said fuel flow when a predetermined value of engine speed is exceeded, and wherein said rotating means is operated by said drive shaft.

11. Control apparatus as set forth in claim 4, including a second valve guide and a second valve slidable therein for controlling second and third pressures respectively in corresponding second and third portions ofV said conduit means,

means for operating said second. valve"y ree sponse to an operating pressure in said engine, a. conduit connected to said third portion ofi said conduit means for the flow of. fluid. therefrom, a restriction in said conduit, operating means responsive to the differential between said second pressure and the pressure downstream from restriction for varying the position cf said first connection to vary said two force proportionalities, manually operated means for displacing said control pressure Varying valve from said neutral position to vary the position of said pressure responsive means correspondingl to said neutral position, and means connected to` said rotating means for producing relative rotary motion between said second valve and said sccond valve guide, whereby said fuel iiow varies as a function of the position of said manually operated means and said engine operating pressure.

l2. Control apparatus as set forth in claim il, wherein said restriction is effective to control the rate of change of said pressure differential when said engine operating pressure increases, and including means for changing said pressure diiferential at a relatively faster rate when said engine operating pressure decreases.

13. Fuel control apparatus for an internal combustion engine having associated thcrewi't a pump for delivering fuel thereto and mean for varying said delivery, comprising: a scuro of hydraulic fluid at substantiaily constarnl superatmospheric pressure, first and second ccnduit means for the flow of uid from said source, a first valve in said rst conduit means for con trolling the flow therethrough to regulate the pressure in a portion thereof, said delivery ing means being actuated by said regulated pres sure, control means for operating said first vaive, restricting means in said second conduit means for establishing a pressure differential there across, a second valve in said second Aconduit means downstream from said restricting means, said second valve being responsive to a temperature in said engine and effective to vary said differential and hence the pressure downstream from said restricting means as a predetermined function of said temperature', a piston responsive to said downstream pressure for overriding said control means in a sense to reducev said fuel fi'ow when the value of said downstream pressure falls below a pre-established value corresponding to a predetermined value of said temperature, and means for varying the relationship between said temperature and said pre-established value, whereby said fuel flow varies asa function of the position of said control means and said temperature when the latter exceeds said predetermined value.

14. Fuel control apparatus for an internal combustion engine having associated therewith a pump for delivering fuel thereto. and means for varying said delivery, comprising: a source of hydraulic fluid at superatmospheric pressure, conduit means for the flow of fluid from said source, control means for controlling a pressure in a portion of said conduit means, said delivery varying means being actuated by said controlied pressure, a piston guide having a pair of ports therein, first and second conduits connecting said ports to said source, a piston slidable in said piston guide and means for rotating said piston, said piston having a chamber at one end thereof and being slotted so that it is` effective when rctated to intermittently afford passage for fiow from said ports corresponding to` said first and second conduits to saidI chamber; a third conduit for flow of fluid from said chamber, and' a valve in said third conduit responsive to a temperature in said engine; said valve' being normally closed and effective when a predetermined value of said temperature is exceeded to permit flow from said first and second conduits through said ports, said chamber, and said third conduit past sai'dj valve and to thereby vary theY pressure in said chamber as a function of said temperature; said piston being responsive to said chamber pressure and effective when said chamber pressure falls below a pre-established value corresponding toa preselected value of said temperature to override said control means inA a sense to reduce said' fuel flow, whereby saidy fuel flow varies as a function of the operation of said first controll means and said temperature when the latter exceeds said predetermined value.

l5. Control means as set forthl in claim 14, including means for cutting off theY flow in said second conduit to decrease` said chamber pressure value corresponding to said preselected value' of said temperature below said pre-established value, so that said pre-establishedA pressure` is not reached until said temperature reaches a second value higher than said preselected value.

l5. Fuel control apparatus for an internal'combustion engine having associated therewith a pump for delivering fuel thereto and means for varying said delivery, comprising: a source of hydraulic fluid, a fluid pump having the' inlet thereof connected to said source and' means for maintaniing a substantially constant superate mospheric pressurev at the outlet of said fluid pump, conduit means forV the flow of' fluid' from said pump to said delivery varying means, control means connected in' series with' saidI conduit means for controlling a pressure in a' portion of said conduit means, means far' actuatingl said delivery varying means by the direct application thereto of said controlled pressureV and effective to increase said fuel' flow as saidv controlled' pressure increases, first means responsive to a temperature in said engine and effective only when a predetermined value of said temperature' is' exceeded to override saidgcontrol' means' soas' to reduce said controlledV pressure and hence said fuel flow, andV second means for varyingV the' response of said first means to said predetermined value of said' temperature.

' i7. Fuel control apparatus for an internal combustion engine having' associated therewith' a pump for delivering fuel thereto and means for varying said delivery, comprising: a source of hydraulic fluid at superatmo'spheric pressure, conduit means for the flow of fluid from said source to said delivery varying means, control means connected in series with said conduit means for controlling a pressure in a portion of said conduit means, means for actuating said delivery' varying means by the direct application thereto of said controlled pressure, a device responsive to the engine speed, governor means, controlled by a manual control and responsive to said device, for operating said pressure control means in a sense to reduce said fuel flow when a predetermined value of said speed as determined by said manualI control is exceeded, and adjustable stop means for limiting the Inovement of said varying means to determinek the maximum speed va'lue 18. Control apparatus asls'et forth inclaim'; 17., including a springk opposing: motion off saidY speed responsive device in response to an increase in speed, a cam, means for operating said cam, a follower operated by said cam, means for varying said deflection of said spring, a motion-transmitting connection between said follower and said deflection varying means, a stop for limiting motion of said deflection varying means in a speed increasing sense to determine the maximum value of said speed, and means in said connection for permitting relative motion between said follower and said deiiection varying means when said cani operates said follower so as to move said deflection varying means against said stop, whereby movement of said cam operating means is not affected by said stop.

19. Fuel control apparatus for an internal combustion engine having associated therewith a pump for delivering fuel thereto and means for varying said delivery, comprising: a source of hydraulic fluid, a fluid pump having the inlet thereof connected to said source, conduit means for the ow of fluid from the outlet of said pump, a first valve for controlling a first pressure in a first portion of said conduit means, said delivery varying means being actuated by said first pressure, movable means for operating said nrst valve to vary said rst pressure, a piston responsive to said lirst pressure and spring means for applying a force on said piston in opposition to said first pressure, a connection between said piston and said first valve to maintain the value of said first pressure proportional to said force, said valve, piston and connection cooperating to maintain a predetermined relationship between said first pressure and the position of said movable means, a second valve for controlling second and third pressures in second and third portions of said conduit means, respectively, means responsive to the differential between said second and third pressures for varying said force to vary said predetermined relationship, a cam in said dilferential responsive means for determining the functional relationship between said differential and said force, guides for each of said valves and said piston and a shaft driven by said engine for simultaneously operating said fluid pump and producing relative rotation between said valves, said piston and their respective guides to prevent sticking of said valves and said piston, whereby said fuel flow is varied by operation of said :rst means and said second value.

20. Control apparatus as set forth in claim 19, including means responsive to a temperature in said engine and effective when a predetermined value of said temperature is exceeded to override said lirst means in a sense to reduce said fuel flow, and means responsive to said movable means and effective within a preselected range of operation of said movable means to vary said predetermined value of said temperature.

2l. Control apparatus as set forth in claim 19, including means responsive to the speed of said engine for overriding said movable means in a sense to reduce said fuel flow when a predetermined value of said speed is exceeded, a control shaft for operating said movable means, means operable by said control shaft for varying said predetermined value of speed, and means for rendering said speed varying means ineffective to increase said speed above a pre-established value.

22. Fuel control apparatus for an internal combustion engine having associated therewith a pump for delivering fuel thereto and means for varying said delivery, comprising: a source of hydraulic fluid, a fluid pump having the inlet thereof connected to said source, conduit means for the flow of fluid from the outlet of said pump, first control means and loading means for applying a force thereto, said first control means being effective to control a first pressure in a rst portion of said conduit means, said delivery varying means being responsive to said first pressure, second control means for modifying said first pressure; said second control means comprising a pilot valve for controlling second and third pressures respectively in second and third portions of said conduit means, means responsive to a pressure in said engine for operating said pilot valve to oppositely vary'said second and said third pressures, a piston having first and second expansible chambers at the opposite ends thereof, said piston being responsive to the differential between the respective pressures in said chambers, and effective to vary said force to modify said first pressure as a function of the position of said piston, first and second conduits for flowing fluid between said third portion of said conduit means and said second chamber, a third conduit for transmitting said second pressure to said first chamber, a restriction in said first conduit for controlling the flow therethrough, a check valve in said second conduit for preventing ow from said third portion to said second chamber, a connection responsive to said piston for positioning said pilot valve, said connection being eective when said engine pressure responsive means is stationary to operate said pilot valve to shut-off position and to maintain a predetermined relationship between the position of said piston and the Value of said engine pressure, said restriction being effective to control the rate of change of said piston position as said engine pressure varies in a sense to increase said third pressure, said check-valve being effective to render said restriction ineiective to control the rate of change of said piston position as said engine pressure varies in a to decrease said third pressure.

23. Control apparatus for an internal combustion engine, comprising means for controlling the supply of fuel to said engine, engine speed responsive means for continuously operating said fuel supply controlling means to maintain said engine speed at a substantially ccnstant value, means responsive to a temperature in said engine for operating said fuel supply controlling means to reduce the fuel supply when said temperature exceeds a predetermined value, manually operable adjusting means for controlling said speed responsive means to vary said substantially constant speed value, means operatively connected with said adjusting means and operable when said substantially constant speed is set at a predetermined value to Vincrease the temperature Value at which' said ternperature responsive means becomes effective to reduce said fuel supply.

24. Control apparatus for an internal combustion engine, comprising means for controlling the supply of fuel to said engine in response to a variable control fluid pressure, and means for controlling said variable pressure including a barometric control system, a speed responsive control system, and a main control system, each of said systems comprising a valve guide, a valve translatable and rotatable in said guide, a cylinder, a piston translatable and rotatable in said cylinder, and means for subjecting at least one end of said piston to a pressure controlled by its associated valve, a base casting, a mounting casting for connecting said base casting to said engine, a shaft driven by said engine and extending into said mounting casting, said base casting having parallel bores therein for receiving said cylinders and at least one of said valve guides, and gearing means driven by said shaft for continuously rotating all said valves and at least one of said pistons at proportioned rotary speeds.

25. Control apparatus as set forth in claim 24, including pressure responsive means in said barometric control system for operating the valve therein, speed responsive in speed responsive control system For operating the valve therein, manually operable means in said main control system for operating the valve therein, and a bracket mounted on the face of said base casting opposite said mounting casting supporting said pressure responsive means, said speed responsive means and said manually operable means.

26. Control apparatus as set forth in claim 25, incuding adjusting means for said pressure responsive means, adjusting means for said speed responsive means, adjusting means for said manually operable means, all said adjusting means being mounted on said bracket, and a cover attached to said base casting and enclosing all the parts mounted on said bracket, so that all said adjusting means are accessible upon removal of said cover.

27. Control apparatus as set forth in claim including a nrst coupling on one of said adjusting means extending toward said cover, a control element adjustably mounted in said cover and extending both inwardly and outwardly therefrom, a second coupling on the inner end of said element and adapted to mate with said rst coupling, and means on the outer end of said element for adjusting it.

28. Control apparatus as set forth in claim 24, including a manually operable control shaft extending into said base casting, and means on said shaft within said casting for controlling said speed responsive system and said main system.

29. Control apparatus as set forth in claim 24, including a speed responsive device in said speed responsive control system, an extension shaft operated by said engine driven shaft for driving said speed responsive device, said extension shaft being mounted in said base casting and removable therewith from said mounting casting, said bracket, and said cover.

30. Control apparatus, comprising a supporting casting, a drive shaft extending through said casting, a base casting supported by said supporting casting, cooperating valve and seat elements in said rbase casting rotatable and slidable relative to each other, cooperating piston and cylinder elements in said base casting rotatable and slidable relative to each other, means connecting one of each set of cooperating elements to said drive shaft to produce proportioned relative rotation thereof, fluid connections between said valve and seat elements whereby said valve controls a iiuid pressure on at least one end of said piston, means mounted on said base casting for positioning said valve, a load device mounted on said base casting and connected to said piston to be positioned thereby, and a cover for said base casting enclosing said positioning means and said load device.

31. Control appara-tus as in claim 30, including a pump in said supporting casting driven by said shaft, a fluid connection between the outlet of said pump and said valve, a fluid connection between said valve and the space inside said cover which constitutes a reservoir, said valve being effestive to control. said pressure by selectively connecting said one piston end to said pump outlet or to said reservoir, and a drain connection between said reservoir and the inlet of said pump.

32. Fuel control apparatus for an internal combustion engine having associated therewith a pump for delivering fuel thereto and means for varying said delivery, comprising: a source of hydraulic fluid at superatmospheric pressure, conduit means for the iioW of fluid from said source, control means in said conduit means for controlling a pressure in a portion of said conduit means, said delivery varying means being actuated by said controlled pressure, a device responsive to the engine speed, governor means responsive to said device for operating said control means in a sense to reduce said fuel i'low when a predetermined value of said speed is exceeded, means for varying said predetermined value of speed, and adjustable stop means for limiting the movement of said varying means to determine the maximum speed value; manual means for operating said control means, means responsive to a temperature in said engine and effective when a predetermined temperature is exceeded to override said control means in a sense to reduce said fuel flow, and means operated by said manual means for varying said predetermined temperature.

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